The present invention relates to a machine for measuring and mathematically defining the surface of three-dimensional models, particularly for the manufacture of molds by means of automated systems comprising numeric-control machine tools.
The preliminary execution of a three-dimensional model of the part or article to be reproduced in series with the subsequent molding process is fundamentally important for the design and manufacture of molds intended for the production of sheet-metal elements or plastic products for the car industry or for the manufacturing industry in general. The three-dimensional model--generally in soft material such as plasticine, polystyrene, wood, resin or the like--in fact allows to check the styling of the design and its accurate preliminary aerodynamic and/or structural testing where required, but it is most of all the starting point for the subsequent manufacture of the mold.
Devices for the three-dimensional measurement of models, capable of supplying an electronic processing system (so-called CAD-CAM systems) with the Cartersian coordinates of a set of points of the model's surface to obtain the so-called mathematical definition of the surface, have been recently produced for this purpose.
Currently known and employed measurement devices generally use mechanical surface feelers which, though they achieve their purpose, have hardly negligible disadvantages and limitations in use. These disadvantages and limitations are substantially constituted by the need to limit the scanning rate, i.e. the rate at which the feeler explores the surface, in order to ensure a correct feeler-surface contact; the structural complexity and therefore the cost of mechanical feelers; the possibility of jamming, and, the need to correlate the shape of the measurement feeler to that of the tool of the machine which generates the mold to reduce the complexity of the programs for processing the information transmitted by said feeler.